High speed diverter

ABSTRACT

A diverter assembly for handling articles transported on a conveying surface is disclosed. The diverter assembly includes at least one diverter arm and a motor coupled to a drive arrangement for swinging the diverter arm over the conveying surface. An inverter controller is provided for operating the motor at a plurality of speeds. A sensor arrangement is coupled to the inverter controller for monitoring the position of the diverter arm. The sensor arrangement sends a slow-down signal to the inverter controller when the diverter arm reaches a pre-determined position, causing the inverter controller to operate the motor at a slower speed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/537,234, filed Aug. 6, 2009, entitled “HIGH SPEED DIVERTER”,currently pending, which claims priority to U.S. Provisional ApplicationNo. 61/086,475, filed Aug. 6, 2008. The entire contents of these relatedapplications are incorporated herein by reference in their entirety.

TECHNICAL FIELD

This invention generally relates to a technology for handling articlesand, in particular, to diverting articles on a conveying surface.

BACKGROUND

Article handling systems, such as those used in airports to handlebaggage, typically include diverters for diverting or sorting articlestransported on a conveyor. Diverters may include arms that are pivotablymounted adjacent to the conveyor. The arms are driven to move across thesurface of the conveyor to divert an article being transported on theconveying surface.

In order to increase the throughput of the articles, it is desirable todrive the diverters at high speed. However, the faster the diverters areoperated, the greater the equipment vibrates and the impact caused onthe articles. This can result in damage to the articles that are beingdiverted as well as being very noisy during operation.

In addition, conventional diverter systems tend to be mechanicallycomplex with many components subject to wear and tear. For example, beltsystems are typically incorporated to drive the swinging of the diverterarms. Such belt systems require tension adjustment and replacement overtime. In order to adjust and replace the belts, the diverter system hasto be disassembled, resulting in long down-times for maintenance.

Therefore, there is a need for a diverter that can be operated at highspeeds while generating less vibrations and impact on diverted articles.In addition, there is a need for a simpler diverter drive system withfewer components, which is less costly to maintain.

SUMMARY

A diverter assembly for handling articles transported on a conveyingsurface is described herein. The diverter assembly includes at least onediverter arm and a motor coupled to a drive arrangement for swinging thediverter arm over the conveying surface. An inverter controller isprovided for operating the motor at a plurality of speeds. A sensorarrangement is coupled to the inverter controller for monitoring theposition of the diverter arm. The sensor arrangement sends a slow-downsignal to the inverter controller when the diverter arm reaches apre-determined position, causing the inverter controller to operate themotor at a slower speed.

Other objects, features and advantages of the invention will become moreapparent upon study of the following detailed description taken inconjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The same numbers are used throughout the drawings to reference likeelements and features.

FIGS. 1 a-b show an embodiment of a conveyor system with a divertingassembly in home and divert positions.

FIG. 2 is another embodiment of a conveyor system.

FIG. 3 is an exploded perspective view of an exemplary diverterassembly.

FIG. 4 is a perspective view of an exemplary diverter arm unit.

FIG. 5 is an exploded perspective view of the exemplary diverter armunit.

FIG. 6 is a perspective view of an exemplary drive chain for a divertingassembly.

FIG. 7 is an exploded perspective view of the exemplary link unit.

FIG. 8 is a plan view of exemplary link and drive units.

FIG. 9 is an exploded perspective view of an exemplary sensorarrangement.

FIG. 10 illustrates an exemplary controller for a diverter assembly.

FIGS. 11 a-e illustrate shot screens for programming an embodiment of aninverter controller.

FIG. 12 illustrates a timing diagram of operating the diverter arms.

FIG. 13 illustrates a speed versus time diagram for the operation of thediverter arms.

DETAILED DESCRIPTION

The following description sets forth various embodiments of a diverterassembly. The diverter assembly may be used in many applications,including but not limited to airport baggage handling systems fordiverting bags, article sorting systems and the like.

FIGS. 1 a-b show a portion of a conveying system 100 in a divert areawhich incorporates an embodiment of a diverter assembly 120. FIG. 1 ashows the diverter assembly in the home (non-divert) position while FIG.1 b shows the diverting assembly in the active (divert) position. Theconveying system, for example, includes first and second conveyors 111and 116 with first and second conveying surfaces 113 and 118. The firstand second conveyors may have different origination and destinationpoints. In one embodiment, the first and second conveying surfacescomprise belt surfaces. Other types of surfaces, such as driven rollers,other driven surfaces or non-driven surfaces, may also be used. Rails138 can be provided on sides of the conveyors to maintain packages beingconveyed within the conveyors.

The conveying surface of the first or primary conveyor moves in a firstdirection (as indicated by arrows 114); the second conveying surface ofthe second or secondary conveyor moves in a second direction (asindicated by arrows 119). Preferably, the second direction continuesforward along the first direction after diversion. For example, asshown, the first and second directions are parallel and in the samedirection. Alternatively, the first and second directions can also be atan angle, such as about 45°, as shown in FIG. 2. Other angles orconfigurations of first and second directions are also useful.

The diverter assembly is disposed in the path of the primary conveyor.In one embodiment, the diverter assembly is mounted onto a diverterassembly frame (not shown) disposed below the primary conveyer. Thediverter assembly includes first and second diverter arms 130 a-bdisposed above the primary conveyor. The diverter arms are positioned onopposite sides of the primary conveyor, mirroring each other. Thediverter arms are rotatable around diverter arm shaft 132 at about afirst end of the arms. The diverter arms are rotated to be in either thehome or divert position.

When the diverter arms are in the home position, the diverter arms areretracted beyond the edges of first conveying surface such that theirlengths are substantially parallel to the sides of the primary conveyor.Articles transported on the primary conveyor are allowed to travel pastthe divert area and remain on primary conveyor.

In one embodiment, when a package is to be diverted, the diverter armsare actuated. Actuating the diverter arms causes them to rotate aroundthe axis of rotation such that they are collinear or substantiallycollinear over the primary conveyor, as shown in FIG. 1 b. For example,the diverter arms are rotated to move the second ends towards eachother. The diverter arms form an angle (divert angle) with respect tothe direction of the primary conveyor. Preferably, the divert angle isabout 45°. In another embodiment, the divert angle can be about 20-60°.Providing other divert angles which can transfer articles from theprimary to the secondary conveyor may also be useful.

In the divert position, the second ends of diverter arms preferablyshould be relatively close to each other to reduce or minimize the gapbetween the arms to avoid articles from being trapped in the gap. Thegap, for example, is about 5-10 mm. Additionally, the height of thediverter arm should be sufficient to divert the articles transported bythe conveyor system. For example, the height of the diverter arm shouldbe at least ½ the height of the tallest article being transported.Preferably, the height of the diverter arm should be greater than theheight of the tallest article being transported. For example, the heightshould be about ¾ the height of the tallest article being transported.

A diverter arm may include a diverting surface (150 a or 150 b). Thediverting surface, in one embodiment, comprises a rotating or drivenbelt which rotates around the frame of the diverter arm. The belt, forexample, rotates around the frame of the diverter arm in a directionwhich facilitates moving a package from the primary to the secondaryconveyor. The diverting surfaces of the arms are driven in a directionto form a continuous diverting surface to maintain the article moving inthe forward direction. For example, in the illustrative embodiment, thebelts of the diverter arms rotate in a clockwise direction. Thediverting surface preferably maintains the forward speed of the packageat a constant speed as it is diverted to the secondary conveyor.

The speed of the belts depends on the speed of the primary conveyor anddivert angle. In one embodiment, the speed of the belts is equal toabout conveyor speed/cos θ, where θ is the divert angle. For example, inthe case where θ is equal to 45°, the speed of the diverting surface canbe about 1.4 times the conveyor speed. Driving the belts at other speedsmay also be useful. In another embodiment, the belt speed is about 10%to 100% above the conveying speed of the primary conveyor.

A diverter arm guard 124 may be provided. As shown, the diverter armguard is provided on an exposed side of the first conveyor. Forapplications in which both sides of the conveyor may be exposed, guardscan be provided for both sides.

FIG. 2 shows an alternative embodiment of a conveyor system 100 in adivert area with a diverter assembly 120 in greater detail. The conveyorsystem includes a primary conveyor 111 with a first conveying surface113 and a secondary conveyor 116 with a second conveying surface 118.The conveying surface 113 of the first or primary conveyor moves in afirst direction (as indicated by arrows 114); the second conveyingsurface 118 of the second or secondary conveyor moves in a seconddirection (as indicated by arrows 119). As shown, the secondary conveyoris merged with the primary conveyor (merged conveyors) at an angle ofabout 45°. Having merged conveyors at other angles may also be useful.Other types of conveyor layouts are also useful, depending on the flowrequirements of the application.

The diverter assembly is disposed in the path of the primary conveyor.In one embodiment, the diverter assembly includes a frame (not shown)disposed below the primary conveyer. Mounted to the frame and above theprimary conveyor are first and second diverter arms 130 a-b withdiverting surfaces 150 a-b. The diverter arms positioned on oppositesides of the primary conveyor, mirroring each other. The diverter armsare rotatable around a diverter arm shaft 132 at about a first end ofthe arms. The diverter arms are rotated to be in either the home ordivert position, as previously described.

A drive train 250 is provided to drive the diverter arms. The drivetrain, in one embodiment, comprises a drive or drive motor 260, a driveunit 265 and link unit 270. The link unit mechanically couples thediverter arms together. The drive unit couples the link unit to themotor. When the motor rotates, the drive train causes the diverter armsto swing into the divert position or retract back into the homeposition.

In one embodiment, the diverter assembly is capable of producing fastdiverter arm swing time. Swing time refers to the time it takes for adiverter arm to more from one position to the other. For example,diverter swing times of about 0.3-0.5 seconds or less can be achieved toenable handling high article sorting rates, for example, greater than60-80 articles per minute. Furthermore, this fast swing time is achievedsmoothly and accurately without vibrations, which improves reliabilityof the diverter assembly.

FIG. 3 shows a perspective view of one embodiment of a diverter assembly120. Diverter assembly 120 includes first and second diverting arms 130a-b drivingly coupled by a link unit 270. In one embodiment, the linkunit comprises a sprocket chain unit. For example, each diverter arm ismounted onto a diverter arm shaft 132 which includes a sprocket 343 toform a diverter arm unit. The sprockets of the diverter arms are coupledby a chain coupler 372, interconnecting the diverter arm units. Othertypes of link units are also useful.

The diverter arm units are mounted onto a diverter assembly frame 301.In one embodiment, diverter arm mounts 333 are provided which are matedto frame mounts 334. The shaft of a diverter arm passes through themount, enabling it to freely rotate. The mounts can be mated using, forexample, bolts. In one embodiment, at least four bolts are used for eachmount in order to counter extra shock loads during operation. Othertechniques for mounting the diverter arm units to the frame are alsouseful.

A drive unit 265 couples the link unit 270 to a drive motor 260 which iscontrolled by a controller unit 380. Upon receipt of command signalsfrom the controller unit, the drive motor is actuated to cause thediverter arms 130 a-b to move to either the home or divert position. Forexample, if the diverter arms are in the home position, drive motorcauses them to move into the divert position and vice-versa. A diverterarm guard 124 may be provided. As shown, the diverter arm guard isprovided on an exposed side of the first conveyor. For applications inwhich both sides of the conveyor may be exposed, guards can be providedfor both sides.

FIG. 4 is a perspective view of an exemplary diverter arm unit 430. Inone embodiment, diverter arm unit includes a diverter arm 130 with adiverting surface 150 supported by a frame 433 which is mounted onto anarm shaft 132. In the illustrated example, the diverting surface is adriven belt. Other types of surfaces, such as driven rollers, othertypes of driven surfaces or non-driven surfaces, may also be used. Inone embodiment, an arm mount 333 is provided on the arm shaft tofacilitate mounting onto a frame. The diverter arm unit may furtherinclude a sprocket 343, which forms part of the chain-sprocket linkunit. The chain-sprocket link unit will be more fully described below.

FIG. 5 shows an exploded perspective view of the exemplary diverter armunit 430. The diverter arm unit includes a diverter arm frame 531 havingfirst and second ends 521 and 522. In one embodiment, a motorized drumpulley 551 is mounted onto a first end of the arm frame using driveroller mount plates 553. In one embodiment, a free roller 554 is mountedto the second end of the diverter arm frame using free roller mountplates 556. The plates, for example, are bolted to the frame. A belt150, which serves as the diverting surface, is mounted onto rollers toform the diverter arm. The tension of the drive belt can be adjusted byvarying the positions of the rollers via the roller mount plates. Themotorized drive pulley, when activated, rotates or drives the belt.

Top and bottom angular contact bearings 563 and 564 are disposed on topand bottom surfaces of the frame at about the first end when it is to bemounted onto a diverter arm shaft 132. To firmly hold the contactbearings in place, top bearing housing 573, sleeve 576 and bottombearing housing 574 are used. The bearing housings are mounted to thetop and bottom surfaces of the frame using, for example, bolts. Thebottom housing also includes a sprocket mount 575 for mounting asprocket 343 thereto with, for example, bolts. In one embodiment, one ofthe diverter arms is coupled to the drive unit. A yoke connector 578 isprovided in the bottom bearing housing to facilitate coupling with thedrive unit.

The diverter arm is mounted to an upper portion of a diverter arm shaft132. For example, the diverter arm shaft is inserted through bottomangular bearing, sleeve and upper angular bearing. To securely hold thetop bearing onto the shaft, a lock nut 581 with a lock washer 583 can beemployed. This in turn holds the diverter arm securely in place withrespect to the diverter shaft, preventing it from lifting duringoperation. The angular bearings allow the diverter arm to freely rotatearound the diverter shaft. A lower portion of the shaft includes adiverter arm mount 333 for mounting the diverter arm unit to a diverterframe. Cover plates 558 may be provided to cover the exposed portions ofthe top and bottom of the diverter arm to prevent potential damage toarticles.

FIG. 6 shows a perspective view of an embodiment of a drive train 250.The drive train includes a drive motor 260, a drive unit 265 and a chainsprocket link unit 270. FIG. 7 shows an exploded perspective view of anembodiment of a chain-sprocket link unit 270.

Referring to FIGS. 6-7, the link unit is illustrated using diverter armshafts 132 a-b. As shown, a diverter arm shaft is assembled with top andbottom bearing housings 573 and 574 (including bearings) and a sleeve576. A sprocket (343 a or 343 b) is attached to the bottom bearinghousing. For the diverter arm shaft 132 a, which is attached to thedrive unit, the bottom bearing housing includes a yoke connector 578.

The chain link unit includes a coupler 372 which includes chain portions677 a-b connected by connecting rod portions 674. The first and secondchain portions are mated to the first and second sprockets 343 a-b,respectively, of the diverter arms. An adjustor 678 may be provided toadjust the tension or slack in the coupler.

The drive unit includes a drive rod 666 and a swivel arm 635. A firstend of the drive rod is coupled to the yoke connector 578 of the firstdiverter arm shaft 132 a while a second end of the drive rod is coupledto the swivel arm. Coupling of the drive rod to the swivel arm and yokeconnector can be achieved using, for example, rod end bearings andbolts. The swivel arm is in turn coupled to the motor.

When the motor is switched on, it causes the swivel arm to rotate so asto actuate the drive unit, causing the first sprocket of the firstdiverter shaft 132 a to rotate. As first sprocket rotates, it engagesthe first chain portion which is interconnected to the second chain,thereby rotating the second sprocket of the second diverter arm. In thismanner, the diverter arm units may be driven to move generallysimultaneously to swing between the home and divert positions.

In one embodiment, a sensor plate 662 is provided. The sensor plate isdisposed in the drive unit. Sensors are mounted onto the sensor plate todetermine the position of the diverter arms. For example, the sensorsdetect the position of the swivel arm to determine the position of thediverter arms.

In one embodiment, a sensor plate 662 is provided. The sensor plate isdisposed in the drive unit. Sensors are mounted onto the sensor plate todetermine the position of the diverter arms. For example, the sensorsdetect the position of the swivel arm to determine the position of thediverter arms.

FIG. 8 shows a plan view of a portion of an embodiment of a diverterassembly 120 disposed the path of a primary conveyor 111. In particular,the portion shows link unit 270 and drive unit 265 in operation toactuate diverter arms (not shown) on first and second diverter armshafts 132 a-b mounted on a frame 301. First and second sprockets 343a-b are provided on first and second diverter arm shafts, respectively.A coupler 372 having first and second chain portions 677 a-b, which areconnected by connecting rod portions 674, are mated to the first andsecond sprockets 343 a-b to form a chain-sprocket link unit.

The drive unit is coupled to the link unit. In one embodiment, the driveunit comprises a drive rod 666 and swivel arm 635. A first end of thedrive rod is coupled to the yoke connector on the first diverter armshaft while a second end of the drive rod is coupled to the swivel arm.Coupling of the drive rod to the swivel arm and yoke connector can beachieved using, for example, rod end bearings 834 and bolts. The swivelarm is in turn coupled to a motor. The motor, for example, can be footmounted to the base of the frame.

When the motor is switched on, it causes the swivel arm to rotate so asto actuate the drive unit. In one embodiment, the swivel arm is rotatedby the motor in a first direction. The first direction, for example, canbe in a clockwise direction. Rotating the swivel arm in acounter-clockwise direction may also be useful.

When swivel arm is driven by drive motor to position ‘A’, the drivelinkage causes the chain-sprocket link to swing diverter arms (notshown) to a first position. The first position, for example, is thedivert position. When swivel arm is driven by the motor to position ‘B’,chain-sprocket link operates to swing first and second diverter arms toa second position, for example, the home position. Further, when theswing drive motor operates in the same rotational direction as theprevious swing, swivel arm moves from position ‘B’ back to position ‘A’,thereby bringing the diverter arms back to the first or divert position.

In one embodiment, a sensor arrangement 831 is provided on a sensormounting plate 662. The sensor arrangement is used to monitor theposition of the swivel arm as it rotates. For purposes of illustration,sensor arrangement comprises four position sensors 836 a-d. Othersuitable numbers of position sensors and arrangements may also be used.In one embodiment, first and third position sensors 836 a and 836 cpositioned opposite each other are coupled to, in one embodiment, aninverter controller (not shown) for slowing down the swing speed of thediverter arms (e.g., Extend Slow Down and Retract Slow Down ProximitySensors). Second and fourth position sensors 836 b and 836 d, in oneembodiment, are coupled to a programmable logic controller or PLC (notshown) for determining and confirming the diverter arm positions (Extendand Retract Proximity Sensors). These components will be described inmore detail below.

FIG. 9 is an exploded perspective view of an exemplary sensorarrangement 831. The sensor arrangement, in one embodiment, includes asensor mounting plate 662. The sensor mounting plate includes curvedslots 964 on which sensors are mounted. In one embodiment, four sensors836 a-d are mounted onto the sensor plate. The sensors, for example,comprise proximity sensors.

The sensor plate is mounted onto the frame such that the swivel armwhich coupled to the motor through opening 944 rotates within the slots.The swivel arm includes a curved sensor activation plate 938. The sensoractivation plates activates the sensors as it rotates pass them. Forexample, when the diverter arms are in the home position, the swivel armwill be in position ‘B’ (as shown in FIG. 8) with the fourth sensor 836d being activated by the sensor plate. Similarly, when the diverter armsare in the divert position, the swivel arm will be in position ‘A’ (asshown in FIG. 8), causing the sensor plate to activate the secondposition sensor 836 b.

FIG. 10 illustrates an embodiment of controller 380 for operating aconveyor system. In one embodiment, the controller comprises aprogrammable logic controller (PLC) 1002 interconnected to an invertercontroller 1004. The inverter controller may be a programmablecontroller that incorporates, for example, Smart Logic Control to enableit to execute the programmed logic. One example of such a controllerthat is commercially available is the Danfoss VLT Automation Drive FC302 or its equivalent. In one embodiment, a sensor arrangement 831 iscoupled to the PLC and inverter controller. The inverter controllerreceives 3-phase power supply which is supplied to a drive motor 260 ofthe diverter assembly.

The PLC may serve to control the overall operation of the diverterassembly. For example, it may determine which articles are to bediverted or not as they approach the diverter area on the primaryconveyor. In addition, it may also determine whether the position of thediverter arms are to be changed or not, based on the input signals fromthe sensor arrangement. If the diverter arms need to have theirpositions changed, the appropriate command signal is issued by the PLCto the inverter controller. For example, PLC may issue an Extend Commandsignal to change the position of the diverter arms from the home to thedivert position; the Retract Command signal causes the diverter arms tochange from the divert to the home position. The PLC may issue a ResetCommand to reset the positions of the diverter arms in the homeposition. On the other hand, no signals need to be issued if thediverter arms need not have their positions changed.

For example, if an article approaching the divert area has beendetermined that it is to remain on the primary conveyor, the PLC thendetermines the position of the diverter arms based on which sensor isactivated. If the Extend Sensor signal is active, this indicates thatdiverter arms are in the divert position. In such case, the PLC wouldissue a Retract Command to move the diverter arms into the home positionto allow the article to remain on the primary conveyor. If the RetractSensor signal is active, this indicates that diverter arms are in thehome position, which is the correct position. In such case, no signal tochange the position of the diverter arms need to be issued by the PLC.

Once inverter controller 1004 receives a command signal (e.g., ExtendCommand or Retract Commands) from the main PLC to actuate diverter arms,it may take over control of the swinging operation with its own built-inlogic controller (not shown). In particular, the inverter controller1004 may change the speed of rotation of the diverter arms by sendingdifferent preset signals 1006 to drive motor 260, depending on thepositions of the diverter arms. The values of these frequencies may bestored in a memory in the inverter controller 1004. In one embodiment,each swinging operation is carried out with a two-speed control. Whenthe command signal is first received from the main PLC 1002, theinverter controller provides a first signal 1006 a to operate drivemotor. The first signal 1006 a comprises a first preset signal toinitiate a quick start of the drive motor. As the swivel arm (ordiverter arms) rotates, a position sensor in the sensor arrangement 831(e.g., sensor 836 a in FIG. 8) senses that the swivel arm plate hasreached its position and sends a slow down signal to the invertercontroller 1004. The slow down signal may comprise the “Retract speedslow down” or Extend speed slow down” signal, depending on whether thediverter arms are presently being retracted or extended. Upon receipt ofthe slow down signal, inverter controller 1004 then sends a secondpreset frequency to drive motor 260, causing the motor to run at aslower speed and to stop within a preset time delay. The time delay maybe preset at 0.1 seconds or any other suitable values. After the timedelay, the inverter controller ramps down the power to the motor untilit reaches its final position.

Although a two-speed control is described above, it should be understoodthat more than two speeds may be used. By operating the swinging actionof the swivel arm at multiple speeds, the overall switching operationmay be achieved at a very short swing time with smooth and accuratepositioning of the diverter arms. In one embodiment, very short swingtimes of about 0.3-0.5 seconds can be achieved with smooth and precisepositioning of the diverter arms. This allows the handling capacity ofthe diverter system to be increased without the disadvantages attendantin conventional high speed diverter systems.

FIGS. 11 a-e show screen shots of an embodiment of a programming logicfor the Smart Logic Control in an inverter controller. FIG. 11 a shows ascreen shot for logic related to a command for moving the diverter armsfrom, for example, the home to the divert position. At 1109, logic rule0 is accessed. FIG. 11 b shows a screen shot of the programming of logicrule 0. As shown, logic rule 0 is a logical or function of the ExtendCommand and Reset Command from the PLC. If either of these signals areactive, logic rule 0=a logic 1 or True. Referring back to FIG. 11 a, iflogic rule 0 is true (logic 1), the inverter controller initiates a runsequence for the motor at 1110. At 1120 the inverter controller runs themotor at a first preset frequency (e.g., preset ref. 0) to give a quickstart of the motor to move the diverter arms.

At 1119, logic rule 1 is accessed. FIG. 11 b shows a screen shot of theprogramming of logic rule 1. As shown, logic rule 1 is a logical orfunction of the signal from the Extend Slow Down Proximity Sensor orReset Command from the PLC. When either of these signals are active,logic rule 1=a logic 1 or True. Referring back to FIG. 11 a, if logicrule 1 is true (logic 1), the inverter controller causes the motor torun at a second preset frequency (e.g., preset ref. 1) at 1130. Thesecond preset frequency slows down the motor to decelerate the diverterarms. A timer is started at 1140. The motor runs at the second presetfrequency until timer times out based on logic rule 3 at 1149, as shownin FIG. 11 d. After the timer times out, the inverter controller stopsthe motor, at which point, the diverter arms are, for example, in thedivert position.

Referring to FIG. 11 e, a screen shot for logic related to a command formoving the diverter arms from, for example, the divert to the homeposition is shown. At 1104, the inverter controller receives a RetractCommand from the PLC. In response, the inverter controller, at 1105initiates a run sequence for the motor. The controller runs the motor ata first preset frequency (e.g., preset ref. 0) at 1115 to give a quickstart of the motor to move the diverter arms. Upon receiving a signalfrom the Retract Slow Down Proximity Sensor at 1124, the controller runsthe motor at a second preset frequency (e.g., preset ref. 1). The secondpreset frequency slows down the motor to decelerate the diverter arms. Atimer is started at 1135. The motor runs at the second preset frequencyuntil timer times out at 1144. After the timer times out, the invertercontroller stops the motor, at which point, the diverter arms are, forexample, in the home position.

FIG. 12 shows an embodiment of a timing diagram 1200 for operating thediverter assembly. The timing diagram shows signals for an extendoperation 1210 and a retract operation 1220. For an extend operation, atTa, an Extend Command is issued by the PLC to the inverter controller.As shown, the Extend Command signal is about 100 ms in length. Since thediverter arm is in the home position, the Extend and Extend DownProximity Sensors would have inactive signals. The inverter controllerramps up the power supplied to the motor causing it to rotate thediverter arms. The ramp up, for example, is about 50 ms until it reaches100% of the desired power at Tb. Providing other ramp up times may alsouseful. From Tb to Tc, the motor operates at the desired power until Tc.At Tc, the swivel arm has activated the Extend Slow Down ProximitySensor. Once the Extend Slow Down Proximity Sensor signal has beendetected, the inverter controller reduces power to the motor to 75% ofthe desired power and continues to run at 75% until Td, when the timertimes outs. In one embodiment, the timer, for example, is about 100 ms.Providing other time out periods is also useful. At Td, the invertercontroller continues to ramp down to 0% of the power supplied to themotor. The ramp down time, for example, is about 50 ms. Other ramp downtimes may also be useful.

To initiate a retract operation, a Retract Command signal is issued bythe PLC to the inverter controller. The retract operation is similar tothe extend operation with the exception that the initial ramp downreduces the power to 70%.

As illustrated by FIG. 12, the inverter controller ramps up and rampsdown the motor during operation to move the diverter arms from a first(e.g., home) to a second (e.g., divert) position. In one embodiment, theramp up and ramp down phases are about 10-40% of the total time it takesto change position. It is understood that the ramp up and ramp downphases need not the be same duration. In one embodiment, the ramp downphase comprises a multi-stage ramp down phase. For example, asdescribed, the power is ramp down to an intermediate power level to slowdown the diverter arm. The initial ramp down stage may be a time stage.After time expires, the second or final ramp down continues until thediverter arms have reached their final position. In other embodiments,more then two ramp down stages may be provided.

FIG. 13 shows speed vs. time graph 1300 for an embodiment of a diverterassembly. The Graph shows two operating cycles (Cycle 1 and Cycle 2) ofthe diverter assembly, wherein an operating cycle includes extending thediverter arms from home position to the divert position and back to thehome position after the article has been diverted. As can be seen, thedrive motor operates at more than 1200 RPM to result in a change inposition of diverter arms in about 0.5 seconds. Furthermore, this fastswing speed is achieved smoothly while stopping accurately at the divertand home positions.

As described, the inverter controller incorporates a multi-stage rampdown of power to the motor to decelerate the diverter arms before fullystopping. In one embodiment, the multi-stage ramp down comprises firstand second ramp down stages. In other embodiments, more than two rampdown stages can be employed. By ramping down of power to the motor inmultiple stages, the inertia of the diverter arms is reduced, whichresults in reducing or preventing vibration when operating at high swingspeeds.

The inverter controller with multi-stage ramping down of power can beemployed for other diverter assemblies. For example, diverter assemblieshaving a single diverter is also useful. In alternative embodiments, thediverter arm or arms of the diverter assembly may be linearly shiftedinto the home or divert position.

Although the one or more above-described implementations have beendescribed in language specific to structural features and/ormethodological steps, it is to be understood that other implementationsmay be practiced without the specific features or steps described.Rather, the specific features and steps are disclosed as preferred formsof one or more implementations.

1. A diverter assembly for handling articles transported on a conveyingsurface, comprising: at least one diverter arm positioned adjacent to aside of the conveying surface; a motor coupled to a drive arrangementfor moving the diverter arm over the conveying surface; a controllerunit coupled to the motor for operating the motor at a plurality ofspeeds; and a sensor arrangement coupled to the controller unit formonitoring the position of the diverter arm, wherein the sensorarrangement sends a signal to the controller unit when the diverter armreaches a pre-determined position, wherein the controller unit operatesthe motor at a slower speed in response to the signal from the sensorarrangement.
 2. The diverter assembly of claim 1 wherein the controllerunit comprises a first controller and a second controller.
 3. Thediverter assembly of claim 2 wherein the first controller comprises aprogrammable logic controller and the second controller comprises aninverter controller.
 4. The diverter assembly of claim 3 wherein thesensor arrangement comprises a plurality of position sensors.
 5. Thediverter assembly of claim 4 wherein at least one position sensor iscoupled to the programmable logic controller and at least one positionsensor is coupled to the inverter controller.
 6. The diverter assemblyof claim 4 wherein the sensor arrangement comprises four positionsensors.
 7. The diverter assembly of claim 1 wherein the drivearrangement includes a drive rod and a swivel arm.
 8. The diverterassembly of claim 7 wherein the sensor arrangement includes a sensormounting plate.
 9. The diverter assembly of claim 8 wherein the sensormounting plate includes a slot on which sensor is mounted.
 10. Thediverter assembly of claim 9 wherein the slot comprises a curved slot.11. The diverter assembly of claim 1 wherein the plurality of speedscomprises at least two different speeds.
 12. The diverter assembly ofclaim 1 wherein the diverter arm is operable to move from the firstposition to the second position in about 0.3-0.5 seconds.
 13. A methodfor handling articles transported on a conveying surface comprising:providing a diverter assembly having at least one diverter armpositioned adjacent to a side of the conveying surface; determiningwhether the diverter arm is in a first position; operating a motor ofthe diverter assembly at a plurality of speeds; moving the diverter armfrom the first position to a second position at a first speed;monitoring the position of the diverter arm, wherein when the diverterarm reaches a pre-determined position, operating the motor at a secondspeed.
 14. The method of claim 13 wherein the second speed is slowerthan the first speed.
 15. The method of claim 14 further comprisesmoving the diverter arm from the predetermined position to the secondposition.
 16. The method of claim 13 wherein monitoring the position ofthe diverter arm further includes operating the motor at a third speedwhen the diverter arm reaches a second predetermined position.
 17. Themethod of claim 16 wherein the third speed is slower than the secondspeed.
 18. The method of claim 17 further comprises: moving the diverterarm at the third speed from the second-predetermined position to thesecond position.
 19. The method of claim 13 wherein operating the motorof the diverter assembly at a plurality of speeds at different positionsreduces vibration.
 20. A method for handling articles transported on aconveying surface comprising: providing a diverter assembly having atleast one diverter arm positioned adjacent to a side of the conveyingsurface; and operating a motor of the diverter assembly by a controllerto switch the diverter arm from a first position to a second position,wherein power supplied to the motor is ramped down in multiple stages.